关键词: 钙质砂胶结, 应变率效应, 微生物诱导碳酸钙沉积, 微平面模型, 抗侵彻性能

Abstract: Microbially induced calcite precipitation (MICP) is effective to strengthen calcareous sand foundation of reef fortifications via in situ construction, dynamic response and numerical model of MICP-treated calcareous sand is essential to the reef defense design and damage evaluation. The MICP cementation experiment was conducted on calcareous sand from the South China Sea. The strain rate effect of MICP-treated calcareous sand was evaluated through quasi-static uniaxial compression and dynamic mechanical testing using a Split Hopkinson Pressure Bar (SHPB), and user subroutine VUMAT was developed based on the microplane model M7, with material parameters calibrated accordingly. Comparing with the calcareous sand penetration experiments, the numerical simulations demonstrated an increase in the penetration resistance of calcareous sand. The results revealed that the unconfined uniaxial compressive strength of the MICP-treated calcareous sand specimen was 12.31 MPa, and at strain rates of 426 s⁻¹, 1 150 s⁻¹, and 1 712 s⁻¹ on the Hopkinson bar, the dynamic increase factors were 1.117, 1.485, and 1.828, respectively. Rate effect has a negative effect on M7 model penetration simulation by 4.2% DOP contribution. Compared with ordinary calcareous sand, the depth of penetration of MICP-treated calcareous sand was reduced by 40.11% on average, while the average target static resistance increased from 5.21 MPa to 11.89 MPa, indicating a significant increase in the resistance to penetration. These findings provide experimental data and simulation model reference for damage analyses of reef fortifications subjected to high-impact loadings.

Key words: calcareous sand cementation, strain rate effect, microbially induced calcite precipitation, microplane model, anti-penetration performance